Howard M. Myers

Quantitative Method for Studying Microleakage In Vivo and In Vitro

Quantitation of microleakage of dental restorations was evaluated in situ in humans and in vitro using neutron activation of 55Mn. Results are expressed in μg units of uptake per tooth. In general, uptake for all restorations was greater in vivo than in vitro.

The vitreous carbon tooth root replacement system: a surgical discipline

Abstract A total of 141 vitreous carbon tooth root replacements have been inserted into both maxilla and mandible of 92 patients. The surgical procedures developed are simple and require no specialized instruments. Of the 141 vitreous carbon implants placed since September, 1972, 134 (95 %) are still being maintained and are functioning well. Only seven implants (5 %) were not maintained. Of these, all were placed in sockets which showed excessive hemorrhaging. In addition, four of the seven were placed supragingivally. This study continues and the number of implants inserted and put into function grows daily. The clinical observations continue to be favorable.

Vitamin A and Sulfur Metabolism

Keratinizing metaplasia of the mucous epithelia of animal organs occurs as a result of vitamin A deficiency. Extensive descriptions of the gross and microscopic characteristics of this deficiency are already in the literature,1-7 the classical work being that of Wolbach and Howe.1 However, the biochemical mechanism for the production of the keratotic lesion has received relatively little attention until quite recently. The keratotic lesion itself represents, chemically, an accumulation of the protein keratin that has a high content of the sulfur-containing amino acid cystine.8 The lesion may be regarded as a conversion of epithelium that is mucous-secreting to one that forms large amounts of keratin. It can be inferred that vitamin A, in some manner, participates in the regulation of the metabolism of sulfur.